I ordered this pack and paid the default $5 by mistake (with a bit of laziness), and would bet quite a few others had the same experience.

When ordering, you had to enter your amount before adding it to the cart, with $5 as the default. There wasn't an option to change it later that I could find. By the time I realized it couldn't be changed, I was through most of the ordering process and didn't feel like starting over.

It would be interesting to see how much better they would have done with either a more intuitive checkout (assuming I missed an option) or had more options in the process.